Fourteen percent of Americans can’t read well enough to search for programs in a TV guide, according to the U.S. Department of Education’s 2003 National Assessment of Adult Literacy (NAAL).

Meanwhile, more than four out of 10 Americans have basic or below-basic prose skills, according to the study. That means they can sign forms or compare ticket prices for two events. However, they have trouble finding places on a map or calculating the cost of office supplies from a catalog.

So how well are they reading your blog post, Web page or news release?

Rate readability

Americans, on average, don’t read very well, but PR pros do. We make the mistake of writing for ourselves instead of writing for the folks who we’re trying to contact.

To reach real readers:

Aim for 50 or higher on the Flesch Reading Ease scaleIn 1946, lawyer, author and writing consultant Rudolph Flesch published the Flesch Reading Ease formula. This formula computes readability based on the average number of syllables per word and words per sentence. Scores range from 0 to 100. The higher your score is, the easier your copy is to read. Today, this is one of the most widely used readability tests. Flesch is used by The U.S. Department of Defense and many government agencies.

To get your score, use Microsoft Word’s Readability Statistics or The Readability Test Tool. For readable copy, you want to hit 50 or above.

Do you think your topic is too complex to meet this mark? Think again. The Wall Street Journal and Washington Post, among others, consistently hit 50 on the Flesch scale.

Don’t like what you see? To raise your score, shorten your sentences and words.

Consider your readerFor some audiences, you want to make your writing even easier to understand. Here’s what you need to know about writing for certain audiences:

Health care consumers: More than one-quarter of Americans with physical or mental conditions have below-basic prose literacy, according to NAAL.

Seniors: One-third of Americans age 65 or older fall into the lowest level of prose literacy, according to NAAL.

Mobile users: Mobile screens cut understanding in half, according to 2011 research by R.I. Singh and colleagues from the University of Alberta. For these audiences, aim for 60 or higher on the Flesch scale.

One indicator to avoid: Don’t ask readers to rate their own literacy. Of the 40 million adults with the lowest level of reading skills on the NAAL test, only 29 percent said that they didn’t read English well and 34 percent said they didn’t write English well.

Really interesting that reading on a mobile device makes comprehension worse. I would imagine this is partly affected by the fact that people reading on mobile are “on the go,” but it’s definitely something to pay attention to.

I hadn’t heard of the Flesch formula before, and find it very interesting that there is a measurement for readability. Less so that mobile reading cuts comprehension in half. I wonder if that has to do with the overly abbreviated and somewhat incomprehensible manner in which people text message. I’m curious, however, what rating I should aim for when writing for academia. Is there a reference that lists which score is most valuable for which audience?